Alternator output variables
capacity to support not only vehicle loads, but
also provide for complete battery recharging in
a time period corresponding to the shortest drive
cycle for the vehicle application.”
Th ere are other benefi ts to oversizing an alternator.
Potential fuel savings is one.
“Alternators convert mechanical energy into
electrical energy,” Steele says. “Some alternators
are in the high-60s (percent) in terms of effi ciency.
22 Fleet Maintenance | June 2018
If you go up in size a bit, you might get to 72
percent effi ciency. Just those few percentage points
on a 500hp engine can really translate into fuel
savings. Some fl eets have shown a positive ROI
in a year or two.”
One more potential benefi t of an oversized alternator
is life expectancy. Because it is oversized,
it is generally underutilized. Th erefore, it runs
cooler and can last longer.
» This chart illustrates
an output curve, or how
alternator output varies
by engine speed and
Chart courtesy of C.E. Niehoff
Even a half volt
difference can cut
time in half.